Desai had run the half marathon last years too, without training for it, and completed it in three hours, so he hoped to better his running time on Sunday. "I was overconfident and wanted to complete the half marathon in less than three hours. But this time I suffered severe cramps after 17 km," said Desai.

At the finish line, Desai was rushed to the medical camp handled by the Asian Heart Institute (AHI) hospital and given intravenous (IV) fluids. He was shifted to Bombay hospital where he was given further IV fluids and sent home.

"If a young and healthy person does not train before running a marathon, he could suffer muscular or skeletal injuries and suffer dehydration. If an older person runs the marathon without training, it could precipitate into a heart-related problem," said Dr Ashish Contractor, head of preventive cardiology, AHI.

Five other runners needed immediate medical attention. Anjula Handa, 39, fell on her face while running the half marathon and suffered multiple injuries to her lips and right elbow. She was treated at the medical camp and then Bombay hospital.

Dinesh Chandrakar, 43, a scientist from Bhabha Atomic Research Centre, running the full marathon, complained of chest pain while on the sea link. He was taken to Lilavati hospital after which he was sent to Jaslok hospital.

"My husband is stable, but under observation," said his wife, Dr Santwana Chandrakar.

Sunil Lulla, 39, and Janaki Nagraj, 40, injured their legs, while full-marathon participant Charles Corbett, 48, complained of giddiness and stablised after being given oxygen.